Conventional cable networks have long been used to distribute content over physical communication media such as coaxial cables, fiber optic links, etc., to multiple subscribers in a cable network environment. Typical distribution of content includes modulating a signal in accordance with QAM (Quadrature Amplitude Modulation) encoding and then transmitting the modulated QAM signals to multiple subscribers over the physical communication medium. Signals are typically transmitted over the physical communication media are encoded in multiple different channels using multiple RF (Radio Frequency) oscillation rates.
There is currently is no interference mitigation technique built into set-top boxes or subscriber domains (where the set-top boxes reside) to compensate for interference caused by wireless network signals such as those associated with LTE (Long Terminate Evolution) networks. In general, LTE is a wireless network that operates in the same frequency bands as many cable operators. For example, the majority of LTE deployments in the United States are currently taking place in two frequency bands such as band 13 (DL 746-756 MHz, UL 777-787 MHz) for Verizon™ and Band 17 (DL 734-746 MHz, UL 704-716 MHz) for AT&T™, both of which are within operating frequencies used by the cable operators.
Propagation and attenuation characteristics of wireless 700 MHz signals are very different from wireless signals at higher frequencies. For example, these relatively lower frequency signals travel further and are less attenuated by structures, distance, etc., than are higher frequency wireless signals. Thus, presence of such signals in an environment can have a greater interference impact.
Additionally, user operated wireless mobile devices that transmit around this frequency range (e.g., 700-800 MHz) may be located in close proximity to a respective set-top box in a subscriber domain (where the set-top box resides), increasing a likelihood of possible interference with signals transmitted in a coaxial cable. Circuitry in the set-top box that processes the signals may be susceptible to wireless interference as well.
In certain instances, an output from a LTE base station can substantially interfere with signals in a physical cable or set-top box. It is further noted that LTE technology uses so-called Orthogonal Frequency-Division Multiplexing (OFDM) in a respective downlink. This means LTE signals also have a higher peak-to-average ratio (crest factor) than other cellular technologies. Generally speaking, a signal with a higher crest factor will lead to more ingress interference (on radio frequency cable signals) as the wireless signal energy is concentrated in a smaller portion of the allocated bandwidth.
Note that LTE is only one source of possible wireless interference that can affect communications. Other sources of interference can include wireless transmissions in accordance with wireless communication standards (such as GSM—Global System for Mobile Communications, AWS_Advanced Wireless Services, UMTS—Universal Mobile Telecommunications System, etc.) used to transmit data in a wireless environment.